This is a traditional Vietnamese type of general purpose boat that went extinct I believe in the aftermath of the war.
The lifting rudder and stemboard are elegant solutions to windward ability and helm balance, the basket bottom makes a very light and easily driven, therefore fast, vessel. The large lugsails give enough area to make it move in all conditions.
It's hard to see how it could be improved for the job, but tell me what y'all think.

Highly appropriate technology means to me the most efficient use of the readily available materials being used to satisfy actual, not perceived needs so efficiently that it perseveres for many generations of users. These boats which are so cheap and sail so fast in the catching and delivery of fish to feed people are an example, the 50K years of archery use is another, several million years of stone tools, etc.
"Something invented by humans that works so well there is no reason to change it."
Did I say that OK?

Highly appropriate technology means to me the most efficient use of the readily available materials being used to satisfy actual, not perceived needs so efficiently that it perseveres for many generations of users. These boats which are so cheap and sail so fast in the catching and delivery of fish to feed people are an example, the 50K years of archery use is another, several million years of stone tools, etc.
"Something invented by humans that works so well there is no reason to change it." Did I say that OK?

Example of highly appropriate technology. Our modern world only 50 years after this was recorded has lost most of the ability to be this adaptable I am afraid. Confronted with the same problem most of us would starve yet these guys in these frail but perfect-for-the-job cockleshells went out and caught enough fish to keep doing it for a very long time. How long? Hundreds of years at a minimum from my research to be absolute, but I think a lot longer.
Since mankind's artifacts of 200,000 years ago have been found on remote isles (Crete for example) that have never had a land bridge, and Australia was colonized across 90 km crossings at least 40k years ago, I suspect simple boatbuilding technology of frail short lived materials like this (which leave no archaeological record) is quite ancient, therefore fits the definition.